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Echocardiography (Echo)

Echocardiography (Echo)

What is an echocardiogram?

An echocardiogram (also called echo, transthoracic echocardiogram or TTE, exercise or stress echocardiogram, dobutamine stress echocardiogram or DSE, or transesophageal echocardiogram or TEE) is a noninvasive (the skin is not pierced) procedure used to assess the heart's function and structures. A transducer (like a microphone) sends out ultrasonic sound waves at a frequency too high to be heard. When the transducer is placed on your chest at certain locations and angles, the ultrasonic sound waves move through the skin and other body tissues to the heart tissues, where the waves bounce or echo off of the heart structures. The transducer picks up the reflected waves and sends them to a computer. The computer interprets the echoes into images of the heart walls and valves.

Anatomy of the heart, interior view
Click Image to Enlarge

An echocardiogram may utilize one or more of several special  techniques:

  • M-Mode echocardiography. This is the simplest type of echocardiography. It produces an image that is similar to a line tracing rather than an actual picture of heart structures. M-mode echo is useful for measuring heart structures, such as the heart's pumping chambers, the size of the heart itself, and the thickness of the heart walls.

  • Doppler echocardiography. This Doppler technique is used to measure and assess the flow of blood through the heart's chambers and valves. The amount of blood pumped out with each beat is an indication of the heart's ability to function. Also, Doppler can detect abnormal blood flow within the heart, which can indicate a problem with one or more of the heart's four valves.

  • Color Doppler. Color Doppler is an enhanced form of Doppler echocardiography. With color Doppler, different colors are used to designate the direction of blood flow. This simplifies the interpretation of the Doppler technique.

  • 2-D (two-dimensional) echocardiography. This technique is used to "see" the actual motion of the heart structures. A 2-D echo view appears cone-shaped on the monitor, and the real-time motion of the heart's structures can be observed. This enables the physician to see the various heart structures at work and evaluate them.

  • 3-D (three-dimensional) echocardiography. 3-D echo technique captures three-dimensional views of the heart structures with greater depth than 2-D echo. The live or "real time" images allow for a more accurate assessment of heart function by using measurements taken while the heart is beating. 3-D echo shows enhanced views of the heart's anatomy and can be used to determine the appropriate plan of treatment for a person with heart disease.

Why is an echo done?

There are many diseases of the heart that may be detected by echocardiography, including the following:

  • Atherosclerosis (coronary artery disease). Evidence of blockages in the arteries due to fatty material and other substances in the blood stream can sometimes be seen on echocardiography.

  • Aneurysm. A dilation or weakness of a part of the heart muscle or the aorta (the large artery which carries oxygenated blood out of the heart to the rest of the body). In extreme cases, an aneurysm may rupture, which is an emergency situation, due to rapid blood loss out of the blood vessels. Occasionally an aneurysm may occur in the pulmonary arteries or surgical patch areas especially if any intervention, such as balloon angioplasty, has been done previously.

  • Cardiomyopathy. An enlargement of the heart, due to thickening or weakening of the heart muscle.

  • Congenital heart disease. Congenital heart disease refers to one or more of several conditions which are present at birth ("birth defects"). Some congenital heart conditions include:

    • Ventricular septal defect (VSD). In this condition, a hole occurs between the two lower chambers of the heart. Because of this hole, blood from the left ventricle typically flows back into the right ventricle, due to higher pressure in the left ventricle. This causes an extra volume of blood to be pumped into the lungs by the right ventricle, which can create fluid buildup and congestion in the lungs.

    • Transposition of the great vessels. In this condition, the outflow tracts of the aorta and the pulmonary artery are switched during fetal development. This means that unoxygenated blood flows out to the body through the pulmonary artery and oxygenated blood flows back into the lungs through the aorta. By itself, this condition cannot sustain life after birth. However, there are usually accompanying defects that permit some oxygenated blood to reach the rest of the body.

    • Tricuspid atresia. In this condition, the tricuspid valve between the right atrium and right ventricle fails to develop properly. By itself, this would mean that  blood could not be pumped efficiently into the lungs to receive oxygen; however, there are usually accompanying defects that allow some blood to go to the lungs.

  • Heart failure. A condition in which the heart muscle has become weakened to an extent that blood cannot be pumped efficiently, thus causing fluid buildup (congestion) in the lung circulation and blood vessels of the abdomen, legs, ankles, feet, and other parts of the body.

  • Left ventricular hypertrophy (enlargement of the left ventricle). High blood pressure makes the heart work harder causing the muscle of the left ventricle to enlarge.

  • Pericarditis. An inflammation of the sac (thin covering) that surrounds the heart.

  • Valvular heart disease. One or more of the heart's four valves becomes defective, or may be congenitally malformed.

An echocardiogram may be done to further evaluate signs or symptoms of these and other conditions. The echo can detect problems with the heart such as enlargement, abnormalities in motion of the heart wall, blood clots, and heart valve abnormalities. It also measures the strength of the heart muscle (ejection fraction).The echo is more accurate than an ECG, but also more expensive. 

How is an echocardiogram done?

A basic echocardiogram may be done in the doctor's office, a clinic, or in the hospital. For the procedure, you will remove your clothing from the waist up. Privacy will be ensured by using drapes across the chest and limiting access into the procedure room during the test. You will lie on your left side on a table or bed, but may be asked to change position during the procedure. EKG leads may be attached to your chest, so that the echo images can be compared to the EKG tracing during and after the procedure. The echocardiography technician will apply warmed gel to your chest. Then he or she will position the transducer on your chest and use a small amount of pressure to obtain the desired image. The technician will move the transducer around on your chest so that all areas and structures of your heart can be observed. During the test, the different echo techniques described above (M-mode, 2-D, 3-D, Doppler, and color Doppler) may be used. You will not be aware of the different techniques except that during the Doppler or color Doppler, you may hear a "whoosh-whoosh" sound. This whooshing sound is your blood moving through the heart.

Once all the images have been taken, the technician will wipe the gel from your chest, remove the EKG electrode pads, and provide you with privacy to dress. Once the procedure has been completed, you will be able to leave and return to your previous activities, unless your doctor instructs you differently. The procedure usually takes about 30-45 minutes to perform. However, factors, such as schedule delays, emergencies, and other factors may delay the start of your procedure or prolong the length of it.

There are other types of echo procedures beyond the basic exam. These procedures are described below.

  • Exercise (stress) echocardiogram. The initial portion of an exercise echo is similar to the basic echo procedure described above. After the resting echo images have been obtained, you will begin to exercise on a treadmill or stationary bicycle. You will exercise until a target heart rate (determined by the doctor based on your age and physical condition) has been reached, or until you are unable to continue exercising due to chest pain, leg pain, dizziness, severe shortness of breath, or severe fatigue.

    Once the target heart rate has been reached, you will continue to exercise if you are able, as exercise duration is an important piece of your stress test result. Immediately after the end of exercise, you will lie down on the table or bed and the echo procedure will be repeated. The doctor will compare the resting echo with the one done immediately after exercise. Once all the images have been taken, the technician will wipe the gel from your chest, remove the EKG electrode pads, and provide you with privacy to dress.

    Once the procedure has been completed, you will be able to leave and return to your previous activities, unless your doctor instructs you differently. The procedure usually takes about 45 minutes to an hour to perform. However, factors such as schedule delays, emergencies, and other factors may delay the start of your procedure or prolong the length of it.

    Some reasons for having an exercise echocardiography include, but are not limited, the following: 

    • To assess stress or exercise tolerance in patients with known or suspected coronary artery disease 

    • To assess exercise tolerance in patients with specific types of valve disease 

    • To assess limits for safe exercise in patients who are entering a cardiac rehabilitation program and/or those who are recovering from a cardiac event such as heart attack or heart surgery

    • To assess blood pressure levels during exercise

  • Dobutamine stress echocardiography (DSE). Dobutamine is a medication given by IV that stimulates the heart and mimics the effects of exercise by causing the heart to beat faster and stronger. A dobutamine stress echo is performed as a substitute for an exercise echo, because some people may be unable to exercise on a treadmill or stationary bicycle due to conditions such as:

    • Recent heart attack

    • Severe hypertension (high blood pressure)

    • Severe arrhythmias (heart rate is too fast, too slow, or too irregular)

    • Severe leg pain with exercise due to poor blood flow in the legs

    • Severe asthma, emphysema, or chronic obstructive pulmonary disease (COPD)

    • Aneurysm

    • Pericarditis

    • Arthritis or other orthopedic limitation

    The preparation for the DSE procedure is similar to that of the basic echo described above. In addition, an IV line will be started in your hand or arm, and a blood pressure cuff will be placed on your arm. You may be asked not to take certain medications before the procedure that could interfere with the test results. A baseline assessment of your heart rate and blood pressure will be done.

    The echocardiography technician will apply warmed gel to your chest. Then he or she will position the transducer on your chest and use a small amount of pressure to obtain the desired image. The dobutamine infusion will begin at a rate determined by your weight. The rate of the infusion will be increased every three minutes until you have reached your target heart rate (determined by the doctor based on your age and physical condition) or until the maximum dose of dobutamine has been reached. After the dobutamine is started and after each increase in the dobutamine rate, your blood pressure will be checked, an EKG tracing will be made, and echo images will be obtained. The technician will move the transducer around on your chest so that all areas and structures of your heart can be observed. During the test, the different echo techniques described above (M-mode, 2-D, 3-D, Doppler, and color Doppler) may be used.

    You will not be aware of the different techniques except that during the Doppler or color Doppler, you may hear a "whoosh-whoosh" sound. This whooshing sound is your blood moving through the heart.

    Once you have reached your target heart rate or the maximum amount of the dobutamine, the medication will be stopped. Your heart rate, blood pressure, EKG, and echo will continue to be monitored for 10-15 minutes until they have returned to the baseline state, or close to it. Once all the images have been taken, the technician will wipe the gel from your chest, remove the EKG electrode pads, take out the IV line, and provide you with privacy to dress.

    Once the procedure has been completed, you will be able to leave and return to your previous activities, unless your doctor instructs you differently. A DSE usually takes about one to one and a half hours to perform. However, factors such as schedule delays, emergencies, and other factors may delay the start of your procedure or prolong the length of it.

    Some reasons for having a dobutamine stress echo include, but are not limited to, the following:

    • To assess the heart's function and structure

    • To assess limits for safe exercise in patients who are entering a cardiac rehabilitation program and/or those who are recovering from a cardiac event such as heart attack or heart surgery

    • To assess blood pressure reaction during stress testing

    • To assess stress or exercise tolerance in patients with known or suspected coronary artery disease

    • To assess cardiac status in patients who are about to undergo surgery

  • Transesophageal echocardiography (TEE). Transesophageal echocardiography is done by inserting a probe down your throat (esophagus) to the level of the heart. The TEE transducer works the same as the transducer used for the other echo procedures. However, a clearer image can be obtained, because the sound waves do not have to pass through skin, muscle, or bone tissue. Certain conditions of the heart, such as valve disorders, blood clots or masses inside the heart chambers, dissection (tear) of the lining of the aorta (the artery which carries oxygenated blood from the heart to the body), and implanted prosthetic (artificial) heart valves are better visualized and assessed with TEE.

    TEE may also be used during surgery to assess the cardiac status of patients with known cardiac disease who are undergoing noncardiac procedures, and during heart surgery to evaluate the effects of surgical intervention to the heart, such as bypass surgery or valve repair or replacement.

    For a TEE procedure, you are taken to a special area with echocardiography and EKG equipment. You will undress from the waist up, and EKG pads will be attached to your chest. You will be given a gown to wear. You will lie on a table or bed for the procedure. An intravenous (IV) line is placed in your hand or arm, so that sedative medication can be given. Sedatives are given to help you relax, but you will remain awake enough to assist in the procedure by swallowing as the TEE probe is passed down your throat. A numbing medication will be sprayed in the back of your throat to make passage of the TEE probe more comfortable. The echo images are obtained from various angles, as the doctor can position the TEE probe remotely. Once all the necessary images have been obtained, the TEE probe will be removed from your throat. You will continue to be monitored in a recovery area until your gag reflex returns and you can swallow adequately enough to take fluids without choking and until you are alert enough to leave. Your heart rate, EKG, blood pressure, and breathing rate will be monitored. Your oxygen level may also be monitored. You will need to make arrangements for someone to drive you home after the procedure, as you will not be allowed to drive after having IV sedation.

    A TEE usually takes about two hours to perform. However, the length of the procedure can be affected by factors such as schedule delays, emergencies, and other factors which may delay the start of your procedure or prolong the length of it.

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